Four distinct rock units have been recognized near El Aguacate, in theJanico-Juncalito-La Vega area of the Duarte complex (DominicanRepublic): (1) serpentinites crosscut by numerous diabasic dikes, (2)basalts interbedded with Late Jurassic ribbon cherts, (3) picrites andankaramites relatively enriched in incompatible trace elements, and (4)amphibolites and gneissic amphibolites chemically similar to OceanicPlateau Basalts. Similar Ar-Ar ages of late magmatic amphibole from apicrite, and hornblende from an amphibolite (86.1 +/- 1.3 Ma and 86.7+/- 1.6 Ma, respectively), suggest that the Duarte picrites arecontemporaneous with the Deep Sea Drilling Program Leg 15 and OceanDrilling Program Leg 126 basalts drilled from the Caribbean oceanicplateau. These basalts are associated with sediments containing LateCretaceous faunas. Sr, Nd, and Pb data show that enriched picrites andamphibolites are isotopically similar to mafic lavas from previouslydescribed Caribbean plateau and Galapagos hotspot basalts. Majorelement, trace element, and lead isotopic features of Late Jurassicbasalts and diabases are consistent with those of normal oceanic crustbasalt. However, these basalts differ from typical N-MORB because theyhave lower epsilon Nd ratios that plot within the range of Ocean IslandBasalts. These rocks appear to represent remnants of the CaribbeanJurassic oceanic crust formed from an oceanic ridge possibly close to ahotspot. Later, they were tectonically juxtaposed with Late Cretaceousslices of the Caribbean-Colombian plateau.